Gar*_*ary 36 python prediction pandas data-science
我收到错误:
ValueError: Wrong number of items passed 3, placement implies 1我正在努力弄清楚在哪里,以及我如何开始解决这个问题.
我真的不明白错误的含义; 这让我很难排除故障.我还包括了在我的Jupyter Notebook中触发错误的代码块.
数据很难附加; 所以我不是在寻找任何人试图为我重新创建这个错误.我只是想找到一些关于如何解决这个错误的反馈.
KeyError Traceback (most recent call last)
C:\Users\brennn1\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\indexes\base.py in get_loc(self, key, method, tolerance)
1944 try:
-> 1945 return self._engine.get_loc(key)
1946 except KeyError:
pandas\index.pyx in pandas.index.IndexEngine.get_loc (pandas\index.c:4154)()
pandas\index.pyx in pandas.index.IndexEngine.get_loc (pandas\index.c:4018)()
pandas\hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:12368)()
pandas\hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:12322)()
KeyError: 'predictedY'
During handling of the above exception, another exception occurred:
KeyError Traceback (most recent call last)
C:\Users\brennn1\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\core\internals.py in set(self, item, value, check)
3414 try:
-> 3415 loc = self.items.get_loc(item)
3416 except KeyError:
C:\Users\brennn1\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\indexes\base.py in get_loc(self, key, method, tolerance)
1946 except KeyError:
-> 1947 return self._engine.get_loc(self._maybe_cast_indexer(key))
1948
pandas\index.pyx in pandas.index.IndexEngine.get_loc (pandas\index.c:4154)()
pandas\index.pyx in pandas.index.IndexEngine.get_loc (pandas\index.c:4018)()
pandas\hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:12368)()
pandas\hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:12322)()
KeyError: 'predictedY'
During handling of the above exception, another exception occurred:
ValueError Traceback (most recent call last)
<ipython-input-95-476dc59cd7fa> in <module>()
26 return gp, results
27
---> 28 gp_dailyElectricity, results_dailyElectricity = predictAll(3, 0.04, trainX_dailyElectricity, trainY_dailyElectricity, testX_dailyElectricity, testY_dailyElectricity, testSet_dailyElectricity, 'Daily Electricity')
<ipython-input-95-476dc59cd7fa> in predictAll(theta, nugget, trainX, trainY, testX, testY, testSet, title)
8
9 results = testSet.copy()
---> 10 results['predictedY'] = predictedY
11 results['sigma'] = sigma
12
C:\Users\brennn1\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\core\frame.py in __setitem__(self, key, value)
2355 else:
2356 # set column
-> 2357 self._set_item(key, value)
2358
2359 def _setitem_slice(self, key, value):
C:\Users\brennn1\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\core\frame.py in _set_item(self, key, value)
2422 self._ensure_valid_index(value)
2423 value = self._sanitize_column(key, value)
-> 2424 NDFrame._set_item(self, key, value)
2425
2426 # check if we are modifying a copy
C:\Users\brennn1\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\core\generic.py in _set_item(self, key, value)
1462
1463 def _set_item(self, key, value):
-> 1464 self._data.set(key, value)
1465 self._clear_item_cache()
1466
C:\Users\brennn1\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\core\internals.py in set(self, item, value, check)
3416 except KeyError:
3417 # This item wasn't present, just insert at end
-> 3418 self.insert(len(self.items), item, value)
3419 return
3420
C:\Users\brennn1\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\core\internals.py in insert(self, loc, item, value, allow_duplicates)
3517
3518 block = make_block(values=value, ndim=self.ndim,
-> 3519 placement=slice(loc, loc + 1))
3520
3521 for blkno, count in _fast_count_smallints(self._blknos[loc:]):
C:\Users\brennn1\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\core\internals.py in make_block(values, placement, klass, ndim, dtype, fastpath)
2516 placement=placement, dtype=dtype)
2517
-> 2518 return klass(values, ndim=ndim, fastpath=fastpath, placement=placement)
2519
2520 # TODO: flexible with index=None and/or items=None
C:\Users\brennn1\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\core\internals.py in __init__(self, values, placement, ndim, fastpath)
88 raise ValueError('Wrong number of items passed %d, placement '
89 'implies %d' % (len(self.values),
---> 90 len(self.mgr_locs)))
91
92 @property
ValueError: Wrong number of items passed 3, placement implies 1
我的代码如下:
def predictAll(theta, nugget, trainX, trainY, testX, testY, testSet, title):
gp = gaussian_process.GaussianProcess(theta0=theta, nugget =nugget)
gp.fit(trainX, trainY)
predictedY, MSE = gp.predict(testX, eval_MSE = True)
sigma = np.sqrt(MSE)
results = testSet.copy()
results['predictedY'] = predictedY
results['sigma'] = sigma
print ("Train score R2:", gp.score(trainX, trainY))
print ("Test score R2:", sklearn.metrics.r2_score(testY, predictedY))
plt.figure(figsize = (9,8))
plt.scatter(testY, predictedY)
plt.plot([min(testY), max(testY)], [min(testY), max(testY)], 'r')
plt.xlim([min(testY), max(testY)])
plt.ylim([min(testY), max(testY)])
plt.title('Predicted vs. observed: ' + title)
plt.xlabel('Observed')
plt.ylabel('Predicted')
plt.show()
return gp, results
gp_dailyElectricity, results_dailyElectricity = predictAll(3, 0.04, trainX_dailyElectricity, trainY_dailyElectricity, testX_dailyElectricity, testY_dailyElectricity, testSet_dailyElectricity, 'Daily Electricity')
Sav*_*nry 35
一般来说,这个错误ValueError: Wrong number of items passed 3, placement implies 1表明你试图把太多的鸽子放在太少的鸽笼里.在这种情况下,等式右边的值
results['predictedY'] = predictedY
试图将3个"东西"放入只允许一个的容器中.由于左侧是数据框列,并且可以接受该(列)维上的多个项目,因此您应该看到另一个维度上的项目太多.
在这里,你似乎正在使用sklearn进行建模,这是gaussian_process.GaussianProcess()来自哪里(我猜,但是纠正我并修改问题,如果这是错误的).
现在,您在此处生成y的预测值:
predictedY, MSE = gp.predict(testX, eval_MSE = True)
但是,正如我们从GaussianProcess的文档中看到的那样,predict()返回两个项目.第一个是y,它是阵列式的(强调我的).这意味着它可以有多个维度,或者,对于像我这样的厚头人来说,它可以有多个列 - 看它可以返回(n_samples, n_targets)哪个,取决于testX,可能(1000, 3)(只是选择数字) .因此,您predictedY可能有3列.
如果是这样,当您尝试将具有三个"列"的内容放入单个数据框列时,您将传递3个项目,其中只有1个适合.
Cha*_*uad 28
不确定这是否与您的问题有关，但将来可能与其他人有关：我有类似的错误。原来 df 是空的（有零行），这就是导致我的命令出错的原因。